1. Field of the Invention
The present invention relates to a flat panel display device, controller, and method for displaying images, and more particularly, to a flat panel display device, controller, and method for enhancing display quality by associating a frequency of a lamp with a display frequency.
2. Description of the Prior Art
Liquid crystal display (LCD) monitors can be classified into reflective, transmissive, and transflective LCD monitors. A reflective LCD monitor displays images with an external light source, which penetrates a display panel and is reflected by an internal reflector therein. A transmissive LCD monitor comprises a backlight source behind liquid crystal units, which emits light and penetrates liquid crystal units. A transflective LCD monitor is a combination of the reflective LCD monitor and the transmissive LCD monitor.
In the transmissive LCD monitor, one or multiple cold cathode fluorescent lamps (CCFLs) are used as backlight sources. To emit light, the CCFL is driven by a high voltage source. Then, the CCFL excites mercury vapor therein to a high energy level by discharging the electricity. The excited mercury vapor returns to its initial energy state while the extra energy becomes ultraviolet. Finally, a phosphorescence material, spread on the inner surface of the CCFL, transforms ultraviolet into visible light.
FIG. 1 illustrates a block diagram of a prior art transmissive LCD monitor 100. The LCD monitor 100 includes an image processing circuit 102, a display panel 104, and a backlight module 106. The image processing circuit 102 controls R, G, and B (red, green, and blue) components for each pixel on the display panel 104 to display different color and contrast. The backlight module 106 includes a pulse width modulation (PWM) module 108, a voltage transformation circuit 110, a power source module 112, and a CCFL 114 to provide a light source for displaying images. To drive the CCFL 114, the voltage transformation circuit 110 transforms low-voltage DC power provided by the power source module 112 into high-voltage AC power with high-frequency. The PWM module 108 controls the AC power provided by the voltage transformation circuit 110 to adjust luminance of the CCFL 114. The PWM module 108 controls luminance of the CCFL 114 by adjusting on and off time of the CCFL 114 periodically. Therefore, the PWM module 108 provides a wider dimming range.
Conventionally, the image processing circuit 102 generates control signals through digital signal processing procedures, while the PWM module 108 is implemented by additional analog circuits, so that the image processing circuit 102 and the PWM module 108, causing ripples on the display panel 104, and decreasing quality.